


Extra Credit

by BabysNotaProp (SuzetteB)



Category: Supernatural
Genre: Anal Sex, Bottom Castiel, College Student Castiel, Dean Winchester Talks Dirty, Desk Sex, Destiel Promptober, Frottage, M/M, Nerd Castiel, Plot What Plot/Porn Without Plot, Professor Dean Winchester, Promptober 2018, Rough Sex, Top Dean Winchester, Wall Sex
Language: English
Status: Completed
Published: 2018-10-23
Updated: 2018-10-24
Packaged: 2019-08-06 07:58:14
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 2,266
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/16384259
Author URL: https://archiveofourown.org/users/SuzetteB/pseuds/BabysNotaProp
Summary: Castiel is a college student with a bright mind and eyes for young, handsome Professor Dean Winchester. Castiel wants extra credit and Dean wants to make Cas his. They settle on an arrangement that benefits everyone.





	1. Chapter 1

**Author's Note:**

> Yep, this is literally as filthy as you’re imagining. Also, it’s my first try at bottom!Cas. Let’s see how it goes. 
> 
> Written for Destiel Promptober 2018! The prompt was: college/teacher

“Open book test this Monday,” Professor Winchester railed off quickly as his classroom full of students grew antsy during the last official thirty seconds of class time. “Have pages 299-412 read by then, and phase one of the group projects are due Wednesday. If your group hasn’t started by now, you should probably go ahead and cancel your weekend plans now.”

 

A couple of students let out soft puffs of nervous laughter. The entire class of fifty Intro to Engineering students poured out, except the studious Castiel Novak. He was unassuming in the same trench coat every day, but quickly became Dean’s favorite. Of course, he couldn’t let the rest of the class know that, but they probably had their suspicions.

 

It was hard not to favor Castiel. Not with the way his deep blue eyes looked over wide-rimmed glasses and rise of his chest strained against his dress shirt. He was also smart as a whip, and what he didn’t earn in points, he made up for in extra credit. That was why he was sticking around after class, after all. And after weeks of dancing around the maddening tension surrounding the young college professor and attractive, eager to please student, Dean and Cas had reached an agreement on the terms of extra credit.

 

Their first sexual encounter had taken place six weeks into the semester, and had nothing to do with extra credit. It came after weeks of Dean lecturing while Cas stared up at him with plump lips gracing his pencil, lips biting the wood, and making eye contact while feathering his tongue over the eraser. It came after Cas repeatedly glancing down at Dean’s mouth and sometimes lower while suggesting extra credit. It came after dozens of hands barely brushing and shoulders bumping.

 

It came in the hallway bathroom, after everyone else in class had wandered elsewhere. Grinding against each other hot and rough, the two panted open-mouthed kisses while chasing release between layers of clothes. Hips rolling, Professor Winchester pressed Castiel further against the bathroom door, hands grasping his face as he licked into his mouth.

 

But Cas wasn’t a passive participant. Between Dean’s thrusts, he placed a thigh between the taller man’s legs, earning a moan of pleasure as Dean now had extra friction to enjoy. They came sweating and groaning, hair disshelved and come staining their pants. They parted ways hastily to clean up, and Dean ended up late for his next lecture and Cas decided to skip his next class entirely.

 

The idea of sexual favors in exchange for extra credit points started out as a joke; Dean laughed it off one time Cas came forward after getting “only 90%” on a quiz, but his student smirked darkly and agreed. After one of their trysts in the housekeeping closet, Dean shocked Cas with a proposition.

 

“Mr. Novak,” he addressed, after they had pulled their pants back up. He always called his students by their last names, but it made Cas nervous to hear it that way right after sex. “I would have you know that what we’re doing is highly frowned upon among staff and faculty. If anyone were to know that I’m in a physical relationship with a student, it could cost us dearly.”

 

Cas’ face shifted to that of disappointment. Somewhere along the way, this forbidden infatuation had grown into something more. He found himself asking Professor Winchester about his little brother and favorite TV shows. He thought about him at night, and not just while masturbating. The thought of his feelings not only being unrequited, but pushed away, was shattering.

 

He hung his head low and thought about how awful it would be to have to stop this. He understood it was generally taboo for teachers to date students, but Cas couldn’t imagine not being with this man.

 

Sensing Cas’ sadness, Dean raised his chin. “You misunderstand me,” he explained to two blue eyes glassy with tears. “I said ‘If anyone were to know I was in a physical relationship with a student’. I never said we couldn’t keep it a secret.”

 

Cas’ chest heaved with a deep gasp of relief. “I thought you were breaking up with me.”

 

“Why the hell would I refuse extra credit to my best student?” Dean teased before kissing Cas’ forehead and exiting the room full of buckets and cleaners.

 

And so they continued, Cas’ extra credit piling up so much that it was unclear why he kept going to class. The other students were none the wiser to his extra curricular activities. As a matter of fact, he was still just the nerdy kid to the rest of them. It was all the same to him. This way, he could get fucked by his favorite professor and be left alone by those in his class who didn’t really care for him.

 

Right now, the only thing Cas cared about was his hands held behind his back, his face flat against Mr. Winchester’s desk, and his ass being split wide open by a thick cock while his own dripped thirstily onto the classroom floor.

 

“You like that, baby?” Dean said through gritted teeth as his angry red member pulsed in and out of his student’s hole. “When I fuck you real good?”

 

“Yes, Professor Winchester,” Cas moaned at the stretch. “Like it when you fill me up.”

 

“Tell me what you want, Mr. Novak.”

 

“I want you to hit me where I like it, professor. And then I wanna ride you.”

 

Without another word, Dean released Cas’ hands and flipped him onto his back, pulling his ass off of the desk. Holding Cas’ ankles on either side of his head, Dean railed into him mercilessly, hitting his prostate at every pass. Seeing Cas’ precome rolling down his shaft, Dean grabbed one of Cas’ hands and brought it down between his legs.

 

“Touch yourself, sweetheart,” he directed. “Let me see that pretty cock fuck your hands.”

 

Castiel could hardly follow orders, as Dean was rapidly building the hungry warmth within him. Any grunts Dean made went straight to Cas’ dick, and with the combined sensations of his prostate being stimulated and cock squeezed, Cas came moaning his professor's first name over and over.

 

Before Cas could glance down at the mess he made, Dean yanked him up by his tie and pulled him into a hard, greedy kiss. Cas took control and backed Dean up, wrapping his legs around his waist before Dean hit the wall. Cas placed a foot on either side of Dean and lowered himself onto his shaft, then began bouncing relentlessly.

 

Dean held onto Cas but left most of the movements to him. He was a quivering mess against the wall, uttering Cas’ name on repeat and revelling in how Cas’ hole squeezed him so well.

 

“Fuck yeah, baby… Just like that,” he whispered, feeling his balls tighten. “You take my cock so well. Feels so good. Keep going… oh fuck, Cas. Shit. Cas! Oh god…”

 

Dean’s eyes clamped shut and mouth dropped open as he came, spurting his seed into Cas’ hole and slopping a sticky drop or two onto the floor. Cas kept moving up and down through the increasing wet sounds, only stopping when he felt Dean begin to soften inside him. Thighs burning from the energy exertion, he slipped off of Dean and back onto solid ground.

 

“How many extra credit points for that, Mr. Winchester?” Cas rasped.

 

High on afterglow, Dean smiled and answered, “Baby, at this point you could quit school and still get an honorary master’s degree.”

 

“Hmm,” Cas squinted as he cocked his head. “Then I guess I better step up my game. I’m going for an honorary doctorate.”

 

“Well in that case, I better see you before _and_ after class tomorrow. I have papers that need grading and I get bored sitting at my desk with no one under it with their lips around my cock.”

 

Cas’ eyes darkened imagining himself sucking Dean off under his desk.

 

“Why just before and after? I’m sure you get tired of standing during all your lectures. How about I just stay under there during the entire class?”

 

“Mr. Novak, you truly are the brightest mind in your class. See you tomorrow, don’t be tardy.”

 


	2. Honorary Doctorate

**Summary for the Chapter:**

> Castiel makes good on his promise to give his professor a blowjob during class.

**Notes for the Chapter:**

> Destiel Promptober 2018: MATRIX
> 
> Totally not the original intent from the prompt, but it’s the first thing I thought of and I reeeeally wanted to make another chapter of this story.

“A matrix is a rectangular array of elements, usually numbers,” Professor Winchester recited while pacing around his desk. “We use matrices in mathematics and engineering because often we need to deal with several variables at once, such as the coordinates of a point in the plane are written or in space.”

 

Everything about today was ordinary, to the casual observer, except Castiel Novak was absent. Although it was uncharacteristic, no one paid it any mind, as it was no secret he was doing well enough in Intro to Engineering to afford skipping class at least a couple of times.

 

Dean motioned to the matrix addition problem written on the board and scanned the class for a volunteer.

 

“Ms. Harvelle!”

 

Jo looked up nervously.

 

“When is it possible to add two matrices together?”

 

“Uh…”

 

Mr. Winchester took a seat at his desk, and Castiel crawled as close as he could to the swivel chair from his hidden position behind wood paneling. Taking in the scent of Dean’s heat between his legs, Cas quietly unzipped his pants and found nothing under them but a rapidly enlarging dick.

 

“Page 298, Ms. Harvelle.”

 

As pages flipped in the distance, Cas released Dean’s gorgeous cock from the confines of dress slacks and ran a teasing lick from base to tip. Dean cleared his throat as he awaited Jo to find the answer on the page she obviously didn’t read.

 

“We can add them if they have the same dimensions,” she finally answered.

 

“Excellent,” the professor affirmed as his student took his dick in both hands and began jacking him slowly. “And if two matrices do not have the same size, and they can’t be added, what do we call the sum?”

 

A hand shot up from the back.

 

“Mr. Fitzgerald?”

 

“Not defined, sir.”

 

Cas guided the head of Dean’s cock into his mouth, wanting to taste every inch with his tongue. As he took him in wholly, he cupped his balls and massaged his inner thigh with one of his thumbs. Cas closed his eyes in delight of how large Dean has gotten in his mouth, and he opened up his throat to take in more.

 

Professor Winchester had Anna Milton come up to complete the problem on the board. It took her longer than it should have, which didn’t bother Dean, because he was much too distracted by the blowjob happening right under his desk. He almost whispered in bliss several times, but instead cleared his throat or said a word uncharacteristically loud.

 

“Who can tell me how to multiply matrices?”

 

Cas was sucking hard now, mind blank of all else except how badly he wanted Dean to come in his mouth. The tip hit his throat and Cas swallowed around him, and he noted how Dean shifted in his seat when it was almost too much.

 

Dean was sure he has heard one of his students recite the answer, and he hoped it was at least close, because right now, his mind was fuzzy with lust that kept building as the lecture dragged on. He had lost his train of thought at least once, and couldn’t afford any other distractions.

 

“Three common right angled triangles can be used to obtain — _fuck_ ,” he hissed as Cas nipped a bead of precome out of his slit. Dean sat up straight and coughed when the entire class looked at him in confusion.  

 

Knowing he was close, Cas sucked a vacuum around Dean’s shaft and dug his fingers into Dean’s thighs, alternating between squeezing the base of his cock and massaging his balls. As Dean continued his lecture, he became less and less focused on the words. Unnecessary pauses dropped between words and entire phrases got lost in his throat as Cas brought him to orgasm.

 

Dean was fucking delicious. From the first taste of his cock to his come coating his throat, Castiel absolutely could not get enough, and he chugged at Dean’s pulsating dick until every last drop was sucked out and swallowed. After slipping off Dean’s shaft wet and nasty, Cas sucked a bruise into his inner thigh and pressed his tongue onto Dean’s perineum.

 

“Class dismissed,” Professor Winchester blurted out suddenly, in the middle of Mr. Shurley reading aloud on scalar multiplication. Not questioning it, the class emptied hastily for the weekend, leaving Dean watching the door click shut.

 

He stood up and dragged Cas out from under the desk, lips still swollen from sucking him off and a splatter of come on his chin.

 

“Mr. Novak,” he said darkly. “If you kept going a second longer, I would’ve accidentally given away your position.”

 

“You’re still hard,” Cas observed. Even now, Dean’s dick stood proudly against his lower stomach, red and overstimulated but still erect. “I can make you come again, Mr. Winchester. I can finger that beautiful ass and hit that sweet spot until you’re begging me to fuck you.”

 

Dean’s brow shot up at the assertion. “Did you just tell me you want to fuck me?”

 

“Until your hole is red and wide open, and you’re sure you’ll pass out from how good I make you feel. And then I’m going to keep going.”

 

“Well then, Mr. Novak,” Dean smiled. “You’re well on your way to that doctorate. What are you waiting for? Get on with it.”


End file.
